The only CPU upgrade you will get on your platform is FX-83xx, which is not bad but it's sub-optimal for quality gaming i would say. If you want to go for ryzen you would also have to replace mobo/ram. And even if you do you would end up with a good CPU and a weak GPU. So i suggest making some trade-offs:
1. Going for a new system but with a slightly weaker CPU that Ryzen 5, for example Ryzen 1200, which would be better at gaming than FX-83xx, and getting a better GPU, like 1050Ti or maybe even 1063.
or
2. Getting used FX-8350 and correctly overcloking it like shown here https://www.youtube.com/watch?v=--hAweqSPxI and getting a much better GPU.
3. Intel platform can use DDR3 memory so you can save up on ram and spend it on better GPU/CPU.
Answering to your current question STRICTLY - replacing GPU would be better. Check this video https://www.youtube.com/watch?v=ATpkZLCoZSE - with right set-up you can achieve wonders.